1. Field of the Invention
This invention relates to a termination structure, a termination method and a termination terminal for a high-speed transmission line.
2. Description of the Related Art
According to miniaturization of a semiconductor process in recent years, in a semiconductor chip (an IC chip) used for a high performance server and a high-speed network device, the performance thereof has been enhanced with great impetus. In association with this, the speeding up of signals input into or output from the semiconductor chip has been progressed, thus in next generation semiconductor chip, it is considered that use of approximately 25 Gbit/s per channel becomes common.
As a high-speed transmission line used for digital signal transmission between devices such as communication devices in a distance of approximately 1 to 10 m, a two core coaxial cable having two signal lines for transmitting differential signals is commonly used, but it is needed to use one that has particularly excellent characteristics, in case of ultra-high speed digital signal transmission of approximately 25 Gbit/s as described above.
As a two core coaxial cable used for the high-speed transmission line, one is generally known, the one being obtained by collectively or separately covering two signal lines with an insulation, and winding a metal tape on the periphery of the insulation so as to form an external conductor, the metal tape including a resin tape and a metal layer formed on one surface of the resin tape and comprised of copper or the like.
Conventionally, as the above-mentioned high-speed transmission line, one having a drain wire for grounding of the external conductor is known. In the high-speed transmission line having the drain wire, the drain wire is electrically connected to a ground line such as a substrate by soldering or the like, thereby the external conductor can be easily grounded. However, in the two core coaxial cable having a drain wire, there is a problem that the drain wire has an impact on the electric field distribution of the inside of the cable so as to easily cause characteristics deterioration, thus it cannot be said that the two core coaxial cable having a drain wire is appropriate for the above-mentioned ultra-high speed digital signal transmission.
Consequently, it is preferred to use a high-speed transmission line without the drain wire, however, in this case, the problem is how to connect the external conductor to a ground line such as a substrate.
As shown in FIG. 5, for a conventional high-speed transmission line 51 without the drain wire, a method is used that is configured to directly connect an external conductor 52 exposed at a terminal of the high-speed transmission line 51 to a ground pattern 55 of a substrate 54 by using a solder 57 that is rather much, and to bend signal lines 53 to a side of the substrate 54 so as to connect the signal lines 53 to signal patterns 56.
Meanwhile, prior arts relating to the invention may include U.S. Pat. No. 7,906,730.